This invention relates generally to vacuum filters and more particularly concerns a vacuum filter cartridge specially adapted for pulse-back vacuum applications.
Filters presently used in pulse back vacuum applications have circular cylindrical media configurations. Since the walls are vertical, filtered particulate which contacts the walls tends to remain against the walls even when there is no suction in the intake direction. The pulse-back action momentarily puffs particulate in the reverse direction away from the filter, but some dislodged particulate is recaptured by the filter before gravity settles it to the bottom of the dust canister.
Conical filters are sometimes used in non-pulse-back vacuum applications. Some have a casing on the outside wall of the filter which makes them inefficient or even unsuitable for pulse-back vacuum applications because the casing interferes with the pulse-back action. Even without the outside casing, known conical filters would all be less efficient in a pulse-back vacuum application than the circular cylinder media because falling particulate can descend only until it contacts the increasingly wider base of the media cone.
Furthermore, all of these filters, whether circular cylindrical or conical, have removable parts which must be disengaged to receive the media and re-engaged to secure the media during the media cleaning or replacement processes. Consequently, they not only clog quickly, but they also require inordinate expenditures of time to clean or replace them. The net result is a significant loss in useful operating time. This deficiency is especially troublesome in many construction-type applications. Particulate created by sanding, grinding and cutting wood, plaster, concrete and the like can clog a filter in a matter of minutes. A high percentage of the time and cost of a construction cleaning job is expended on cleaning and replacing filters. The unfortunate alternative presently is to work in a highly dust-contaminated atmosphere.
Another serious problem is encountered because of the complicated mounted structures. The removable components are generally secured by bolts and nuts and the junctions of components surrounding air flow paths are fitted with gaskets. The gaskets are generally not adequate to deal with types and quantities of contaminants encountered in construction applications. Moreover, the vibration of the machine during use, as well as the jostling of the machine during loading, transport and unloading, causes the bolts to loosen. Loosening of the bolts creates gaps in the system at the gaskets and elsewhere which allow collected particulate to be re-circulated through the machine clean air discharge and turbulently released into the atmosphere. In a matter of moments, a room can be filled with drifting particulate which cannot be vacuumed until it settles into every nook and cranny. To prevent this, it is necessary to tighten all of the bolts at the beginning of, as well as intermittently during, each job.
It is, therefore, an object of this invention to provide a barrier filter cartridge which is specially adapted for pulse-back vacuum applications. Another object of this invention is to provide a barrier filter cartridge which operates efficiently in construction-type vacuum applications. A further object of this invention is to provide a barrier filter cartridge which is efficient in collecting particulate resulting from sanding, grinding and cutting wood, plaster, concrete and the like. Yet another object of this invention is to provide a barrier filter cartridge which is efficient in vacuuming a highly dust contaminated atmosphere. It is also an object of this invention to provide a barrier filter cartridge which does not have a circular cylindrical filter media. Still another object of this invention is to provide a barrier filter cartridge which does not have a filter media which widens from top to bottom. An additional object of this invention is to provide a barrier filter cartridge which does not require an outer casing. Another object of this invention is to provide a barrier filter cartridge which does not require disengagement of removable parts to clean or replace the filter. A further object of this invention is to provide a barrier filter cartridge which facilitates cleaning and replacement of the filter. Yet another object of this invention is to provide a barrier filter cartridge which does not require nuts, bolts or gaskets in its assembly. It is also an object of this invention to provide a barrier filter cartridge which does not have components which loosen in response to operating vibration or the jostling experienced during loading, transport and unloading. Still another object of this invention is to provide a barrier filter cartridge which reduces the likelihood of occurrence of gaps via which collected particulate may be re-circulated through the machine clean air passage. And it is an object of this invention to provide a barrier filter cartridge which relieves the necessity for tightening connections of the cartridge before and during each job.